Mitigating Salt Stress in Tomato Plants via Gelidium robustum Seaweed Extract

Abstract

Salinity stress, a major abiotic factor, poses a threat to crops. Thus, strategies to mitigate adverse effects on crops are warranted. This study analyzed the effects of the red seaweed Gelidium robustum extract on tomato plants (Solanum lycopersicum) subjected to salt stress. The composition of seaweed was analyzed by analytical methods, showing that it consists of protein, phenolic compounds, flavonoids, glycine betaine, elements, tannins, proline, and growth hormones. The tomato plants were cultivated under salinity stress (2 to10 dS/m) and treated with seaweed liquid fertilizer (SLF) at various concentrations (2.5% to 10%). The tomato plants treated with SLF presented significant growth-promoting activity. Morphological analysis revealed improved shoot, root, and leaf growth. Compared with no treatment, SLF increased the total protein and fat contents in tomato leaves. Similarly, treatment of tomato plants with SLF improved their flavonoid and phenolic compound contents and antioxidant activity. SLF altered the biochemical profile, alleviated stress, and enhanced defenses. Overall, SLFs have the potential to mitigate salinity stress in tomato plants due to the antioxidant defense, and the application of red seaweed is useful for improving agriculture in salt-contaminated agricultural soils.